IPython pdb

Use

ipdb exports functions to access the IPython debugger, which features tab completion, syntax highlighting, better tracebacks, better introspection with the same interface as the pdb module.

Example usage:

import ipdb
ipdb.set_trace()
ipdb.set_trace(context=5)  # will show five lines of code
                           # instead of the default three lines
                           # or you can set it via IPDB_CONTEXT_SIZE env variable
                           # or setup.cfg file
ipdb.pm()
ipdb.run('x[0] = 3')
result = ipdb.runcall(function, arg0, arg1, kwarg='foo')
result = ipdb.runeval('f(1,2) - 3')

Arguments for set_trace

The set_trace function accepts context which will show as many lines of code as defined, and cond, which accepts boolean values (such as abc == 17) and will start ipdb's interface whenever cond equals to True.

Using configuration file

It's possible to set up context using a .ipdb file on your home folder or setup.cfg on your project folder. You can also set your file location via env var $IPDB_CONFIG. Your environment variable has priority over the home configuration file, which in turn has priority over the setup config file. Currently, only context setting is available.

A valid setup.cfg is as follows

[ipdb]
context=5

A valid .ipdb is as follows

context=5

The post-mortem function, ipdb.pm(), is equivalent to the magic function %debug.

If you install ipdb with a tool which supports setuptools entry points, an ipdb script is made for you. You can use it to debug your python 2 scripts like

$ bin/ipdb mymodule.py

And for python 3

$ bin/ipdb3 mymodule.py

Alternatively with Python 2.7 only, you can also use

$ python -m ipdb mymodule.py

You can also enclose code with the with statement to launch ipdb if an exception is raised:

from ipdb import launch_ipdb_on_exception

with launch_ipdb_on_exception():
    [...]

Issues with stdout

Some tools, like nose fiddle with stdout.

Until ipdb==0.9.4, we tried to guess when we should also fiddle with stdout to support those tools. However, all strategies tried until 0.9.4 have proven brittle.

If you use nose or another tool that fiddles with stdout, you should explicitly ask for stdout fiddling by using ipdb like this

import ipdb
ipdb.sset_trace()
ipdb.spm()

from ipdb import slaunch_ipdb_on_exception
with slaunch_ipdb_on_exception():
    [...]

Development

ipdb source code and tracker are at https://github.com/gotcha/ipdb.

Pull requests should take care of updating the changelog HISTORY.txt.

Manual testing

To test your changes, make use of manual_test.py. Create a virtual environment, install IPython and run python manual_test.py and check if your changes are in effect. If possible, create automated tests for better behaviour control.

Third-party support

Products.PDBDebugMode

Zope2 Products.PDBDebugMode uses ipdb, if available, in place of pdb.

iw.debug

iw.debug allows you to trigger an ipdb debugger on any published object of a Zope2 application.

ipdbplugin

ipdbplugin is a nose test runner plugin that also uses the IPython debugger instead of pdb. (It does not depend on ipdb anymore).